Charles asked:
Please, can you briefly explain the paradigm shift of Thomas Kuhn.
Answer by Jürgen Lawrenz
In The Structure of Scientific Revolutions (1962) Kuhn had come around to the view that our common notion of science as a means of accumulating knowledge is too simple-minded to be true. For example: We don’t know or understand X, so let us run experiments. Involved in this is the assumption of an objective factual state and an objective observer, who asks questions of nature and receives an answer. This result is added to an overarching current theory. The name for the latter is “the current paradigm” and the experimental result is assumed to comprise an enrichment of the paradigmatic coherence.
What if the result does not conform to expectations? Then the experiment was either a failure and must be repeated; or else it is absorbed in the current paradigm as a refractory instance. Now it may happen along with the improvement of experimental techniques, that increasing numbers of experiments contradict the paradigmatic theory, and add embarrassment instead of enrichment. The general belief is, that this is to be expected and that therefore the paradigm will gradually change in accordance with these divergent findings.
Too simple and historically untrue, says Kuhn. Paradigms don’t grow like trees nor change their fruits from cherries to apples in a gradual way. They grow as one or the other; and if the soil becomes uncongenial to cherries, you must stop and seed apple trees. In a like manner, science does not watch one paradigm slowly phasing out and a new one phasing in. There comes a point when the old must be dismembered and the new installed in toto.
The reasons for this are threefold:
(a) We cannot work with two contradictory paradigms side by side. That’s not science, but higgledy-piggledy.
(b) An experimenter is not a ‘neutral’ observer, but a participant, as he builds up the structure and process of experiments from known facts and with a specific target in mind.
(c) It follows from (b) that the current paradigm hovers above the experiment in terms of the expectations associated with it. For this state of affairs Kuhn coined the expression “all experiments are theory-laden”, meaning they are saturated beforehand with the terms of discourse dictated by the current paradigm.
From which, finally, his thesis emerged that paradigmata are never simply abandoned on the strength of mounting contradictions. They are tenaciously held beliefs and will resist even partial demolition for years and even generations. What tends to happen instead, is the emergence of idea that binds all the conflicting new ideas together in a new coherent structure, which will then displace the old by way of a revolution, in a relatively short time. Capital instances of such paradigm shifts were Newton’s synthesis and Einstein’s relativity theory.
Ask a Philosopher 
Andre, You wrote, “when one “proto scientist” first understood that there was an “objective” reality outside of us which we could use and manipulate for our benefit.
What do you consider to be this “objective reality” ? Kant’s thing in itself?
“Capital instances of such paradigm shifts were Newton’s synthesis and Einstein’s relativity theory.”
You forgot the most important of them all, the Copernican Revolution, which opened a new avenue for the later ones. And let’s not forget the most important of them all the Homo Revolution, when one “proto scientist” first understood that there was an “objective” reality outside of us which we could use and manipulate for our benefit.
You’re quite wrong, young man. I didn’t forget; I just threw the two examples in: The questioner did not ask for them. Copernicus is not a good example, because the paradigm arising out of heliocentrism took almost 300 years to be universally acceptable — note I said “universally”. Finally, I’ve not heard of the Homo revolution before — can you give me the date on which this occurred?